The present invention relates to a cramping terminal fitting or an insulation displacement terminal fitting and to a production method therefor.
A prior art cramping terminal fitting is disclosed in Japanese Unexamined Patent Publication 6-333613 and is identified by the numeral 100 in FIGS. 11 and 12 of this application. A middle portion of the prior art cramping terminal fitting 100 is provided with insulation displacement contact (IDC) portions 101 for making cuts in an insulation coating of an unillustrated insulated wire. Each IDC portion 101 is substantially U-shaped and opens upwardly as shown in FIG. 12. Cutting blades 102 are provided at the opening edge of the IDC portion 101 for cutting the insulation coating of the wire, and a contact portion 103 is provided below the cutting blades 102 for contacting the core of the wire.
The cramping terminal fitting is formed from an electrically conductive plate material that is plated for anticorrosion purposes before being pressed. However, the plating comes off the prior art cramping terminal fitting 100 during the formation of cut ends, including the cut ends that define the cutting blades 102 and the contact portion 103. As a result, a second plating needs to be applied after the prior art cramping terminal fitting 100 is shaped by a press. The second plating plates the cut ends that define the cutting blades 102 and the contact portion 103, and thus ensures that a satisfactory contact state is maintained between the contact portion 103 and the wire.
Another prior art electrical connection member is disclosed in EP 0 352 966 B1. The prior art electrical connection member shown in EP 0 352 966 B 1 has a channel into which a wire can be inserted and in which insulation severing edge surfaces are provided. The insulation severing edge surfaces converge toward each other and are dimensioned to contact the wire inserted into the channel. As a result, the insulation severing edge surfaces displace the insulation coating on the wire. This prior art electrical connection member further includes arcuate dimples in the walls of the channel. The arcuate dimples define bowed portions that have crests. Further insertion of the wire into the channel causes the crests of the bowed portions to enter the incisions made by the insulation severing edge surfaces. Thus, the crests of these bowed portions on the prior art electrical connection member contact the core of the wire. However, the core of the wire may be contacted improperly by the bowed portions when the wire is not oriented completely and/or properly.
The present invention was developed in view of the above problem, and an object of the invention is to provide a terminal fitting which comprises an improved cutting blade that can maintain a satisfactory contact state with a wire without applying a second plating after the terminal fitting is shaped by a press.
The subject invention is directed to a terminal fitting for a wire that has an electrically conductive core and an insulation coating. The terminal fitting is formed from an electrically conductive plate member that has been plated on one surface. The plate member is formed to define sidewalls. At least one insulation displacement contact portion is formed between the sidewalls and is open to one side of the terminal fitting. Thus, the wire can be pushed transversely into the insulation displacement contact portion of the terminal fitting. The insulation displacement contact portion comprises cutting blades for cutting the insulation coating and at least one contact portion for contacting the core. The contact portion is below the cutting blades along the insertion direction of the insulated wire, and is defined by an inward embossment on at least one sidewall. The embossment may be of substantially triangular cross section and may be dimensioned for tightly holding the core of the wire. least one sidewall. The embossment may be of substantially triangular cross section and may be dimensioned for tightly holding the core of the wire.
Accordingly, the cutting blades cut the insulation coating and the contact portion, which is provided below the cutting blades, is brought into contact with the core as the insulated wire is pushed further into the insulation displacement contact portion. The contact portion is formed by inward embossments on the sidewalls of the terminal fitting. As a result, a satisfactory contact state can be maintained without peeling the plating on the front surface.
The terminal fitting may further comprise a guide portion above the cutting blades for guiding the wire to the cutting blades. Accordingly, the insulation coating of the wire is cut smoothly since the wire is guided to the cutting blades by the guide portion. The guide portion may have an inclined portion with an inclination angle that is substantially the same as an inclination angle of the cutting blades.
The cutting blades are formed by edges of cut ends that are obtained when the electrically conductive plate member is bent. End positions of the edges are aligned with an upper end of the contact portion.
At least one opening may be formed in a portion of the bottom of the terminal fitting where the insulation displacement contact portion is formed. The opening avoids distortion of the terminal fitting, which could occur when the insulation displacement contact portion is formed by embossing.
According to the invention, there is further provided a method for producing a terminal fitting. The method comprises providing at least one insulation displacement contact portion that is electrically connectable with a core of an insulated wire by making cuts in an insulation coating as the insulated wire is pushed into the insulation displacement contact portion. The insulation displacement contact portion may be formed by embossing one or more opposed sidewalls of the terminal fitting inwardly such that the embossed portions have a substantially triangular cross section. The embossments form one or more cutting blades for making cuts in the insulation coating of the insulated wire and one or more contact portions which are provided below or behind the cutting blades as seen in an insertion direction of the insulated wire. The contact portions then may be brought into contact with the core.
According to a further preferred embodiment, the method further comprises a step of bending an electrically conductive plate member and/or plating a front surface thereof.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings.